It can be easy to forget these days, but Liam Neeson is a real, Oscar-nominated actor who’s played historical figures, famous lit personages and everything. But he’s only slightly less excellent in the Bronsonesque, aging asskickers that have come to dominate his recent career. The key to “Taken,” “The Grey” and the new “Non-Stop” is the gravitas he brings to roles that probably could have been played by Sylvester Stallone or Jean Claude Van Damme or even Eric Roberts. Part of Neeson knows this is junk, but another part of him knows that watching Oskar Schindler bash heads and electrocute baddies shouldn’t be mere novelty.

Neeson’s latest old-ish man thriller finds him as Bill, an air marshal whose latest flight is interrupted by a text from a stranger telling him he or she is a passenger, and he or she demands $150 million or else a passenger will die every 15 minutes. This can be interpreted liberally: The first casualty winds up coming at Bill’s hand, after he’s been successfully pushed in the right direction.

The real twist, though, is that Bill isn’t a hero. He’s a haunted alkie. Like Denzel Washington in “Flight,” he spikes his coffee as he comes on duty. When things get hairy, he doesn’t toughen up; he screws up, immediately losing control of a situation already out of his hands. The passengers quickly come to hate him, because he’s terrible at crowd control and doesn’t remotely seem like he knows what he’s doing, because he doesn’t. A thriller frontperson hasn’t been this enjoyably, hilariously bad at their job since Denzel Washington in “Out of Time.”

Neeson won’t win any awards for this, nor should he. But he dives right in, seeming to delight in playing a characters who’s all flaws, who won’t calm frayed nerves, who can’t intimidate baddies and goodies alike with boasts about his “special set of skills.” He has none — or he has some, as in the lone scene where he brings some hurt during a nifty tussle in the cramped confines of an airplane bathroom. But that's a token gimme to the audience, who will no doubt be confused when Neeson inevitably succeeds, but mostly by accident.

Neeson’s excellent portrayal of badness greatly helps what’s otherwise a mostly routine, extremely silly if sometimes clever programmer, in which every character takes turns as a suspect. It even plays with stereotypes, even if the playing — with potential perps who are Muslim, African American or simply hothead cops — remains questionable. It’s predictable that the whole thing falls amusingly apart in the final stretch; the villainous motive doesn't even makes sense. But it moves reasonably well, and best of all it has personality, not only in Neeson but in Julianne Moore — relaxed and flirty as a passenger who’s either an ideal love interest or an ideal psychopath. With a DTV cast it would be stupid but enjoyable, but with real actors it becomes something else else entirely: stupid but enjoyable and well-acted.